1. Field of the Invention
The present disclosure relates generally to devices with sensors and, more particularly, to devices that dispense volatile materials in response to detection of an environmental condition.
2. Description of the Background of the Invention
Diffusion devices or dispensers are used to dispense volatile materials, such as perfumes, deodorizers, insecticides, insect repellants, and the like. Many such devices are passive diffusion devices that require only ambient air flow to dispense the volatile material, while other devices are active diffusion devices. Active diffusion devices are found in a variety of forms, some include fans and/or heaters to aid in the dispersal of volatile materials, others actuate a valve stem of an aerosol container to dispense a volatile material contained therein, still others utilize an ultrasonic transducer to break up a liquid volatile material into droplets that are ejected from the device, and yet others include any combination of the above or any other known type of active diffusion device. Various examples of such devices can be found in Helf et al. U.S. patent application Ser. No. 11/401,572, Beland et al. U.S. patent application Ser. No. 11/801,554, Helf et al. U.S. patent application Ser. No. 11/893,456, Helf et al. U.S. patent application Ser. No. 11/893,476, Helf et al. U.S. patent application Ser. No. 11/893,489, Helf et al. U.S. patent application Ser. No. 11/893,532, Schwarz U.S. patent application Ser. No. 11/341,046, Sipinski et al. U.S. patent application Ser. No. 12/080,336, and Pedrotti et al. U.S. Pat. No. 6,917,754, all of which are incorporated herein by reference in their entireties. Further, some active diffusion devices include a sensor to detect motion or light in a space, wherein such devices dispense a volatile material in response to signals from the sensor.
Early diffusion devices that included sensors were developed for use in restrooms to dispense perfumes or deodorizers to combat malodors in the restroom. However, when a need arose for such devices in other environments, e.g., a living room, an office space, an outdoor area, etc., prior art devices that were developed for use in the restroom were found to be unsatisfactory. More specifically, the prior art devices were designed to operate in a relatively small space in which ambient light conditions were relatively low and generally stable. Consequently, the sensors of such prior art devices were only configured to function in a narrow range of operating conditions.
Referring to FIG. 1, a basic prior art sensor configuration 10 is depicted that includes a phototransistor 12. A collector electrode of the phototransistor 12 is coupled to a supply voltage level Vcc and an emitter electrode of the phototransistor 12 is coupled via a resistor 14 to a ground voltage level. Varying light levels that reach the phototransistor 12 result in variations in current that flows through the phototransistor 12. The varying current results in a varying voltage level at a bias point 16 that is established at a junction between the phototransistor 12 and the resistor 14. More specifically, the combination of the phototransistor 12 and the resistor 14 results in a linear relationship between the current through the phototransistor 12 and the voltage level at the bias point 16. The voltage level at the bias point 16 is monitored to trigger a motion detect signal, wherein fluctuations in the voltage level at the bias point 16 are interpreted by a controller (not shown) to determine if motion has been sensed by the phototransistor 12, i.e., the variation in light level is interpreted by the controller as motion. Thereafter, the controller is typically configured in such prior art devices to activate a dispensing mechanism to dispense a volatile material into the atmosphere if motion has been sensed.
When such prior art devices are placed in larger spaces with high ambient light conditions, the sensors of the prior art devices do not function properly to detect motion. For example, when a prior art device that incorporates the sensor configuration 10 of FIG. 1 is placed in a living room with high levels of ambient light (see generally FIG. 2), the ambient light in the living room causes a high current to flow through the phototransistor 12. The high current that flows through the phototransistor 12 results in a high voltage level at the bias point 16 because of the linear relationship between the current through the phototransistor 12 and the voltage at the bias point 16. In some cases, the high voltage level approaches the voltage level of the supply voltage. Consequently, a controller coupled to the bias point 16 will have difficulty determining if motion has been sensed based on fluctuations in the voltage level at the bias point. Similarly, in low ambient light conditions, a low current flows through the phototransistor 12 that results in a low voltage level at the bias point 16 that can approach the ground voltage level. In such low ambient light conditions the controller coupled to the bias point 16 similarly has difficulty determining if motion has been sensed. This is because the sensitivity of the sensor configuration 10 is directly and linearly proportional to the ambient light level. Therefore, devices that incorporate the sensor configuration 10 of FIG. 1 often do not have enough sensitivity to operate in a wide range of environments, such as in high and low ambient light conditions.
Further, prior art sensor configurations suffer from an inability to detect motion at substantial distances. For example, in high ambient light conditions, only motion very close to the phototransistor 12 will trigger a motion detect signal. Therefore, motion in portions of the room away from the phototransistor 12 will not trigger a motion detect signal.
Another problem that affects the performance of the prior art devices is the issue of false triggers due to high frequency and low frequency environmental conditions that should be ignored but, instead, are interpreted as the detection of motion in a room. For example, a high frequency condition is the flickering of a fluorescent light in a room (see generally FIG. 2), which will be interpreted as the detection of motion in some prior art devices. Further, a low frequency condition can be a transition in ambient light from afternoon to evening by the setting of the sun through a window of a room (see generally FIG. 2). Likewise, such low frequency light changes can also be interpreted as the detection of motion in some prior art devices. Therefore, there is a need for a dispensing device that solves the various issues discussed hereinabove.